Rotor ventilation for turbogenerators



Jan. 18, 1949. M. D. ROSS ROTOR VEN'I'iLATION FOR TURBO-GENERATORS FiledMay 13, 1947 WITNESSES:

ATTORNEY Patented Jan. 18, 1949 2,459,586

ROTOR VENTILATION FOR TURBOGENER-ATORS Malcolm D. Ross, 'Pittsburgh,Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh,Pa., a corporation of Pennsylvania Application May 13, 1947, Serial No.747,683 2 Claims. (Cl. 171-252) My invention relates to turbogenerators,Figure 1 shows a turbo-generator having a which are synchronousdynamo-electric mastator-member I, carrying a S-phase primary chinesadapted to be direct-connected to a steam Winding 2, and a rotor-member3 which emturbine. Such generators have a very special bodies the novelVentilation-system of my present design, which has been successfullydeveloped 5 invention. .The rotor-member comprises arotorafter years ofexperience, the principal difilculty core 4 which is integral with ashaft 5., As shown being to design the rotor-member to be able to inFig. 2, the rotor-core is provided with subwithstand the extremly largestresses due to stantially axially extending slots 6 which carrycentrifugal force. The design of turbogenerators the coil-sides l of a.concentric field-winding. is in a large measure the design of its rotor.The 10 The field-winding has end-turns 9 which extend' diameter or therotor is strictly limited by the beyond the ends 01' the rotor-core 4,and which peripheral speed, resulting in a machine-design are restrainedagainst centrifugal force by a reof great axial length. The rotor-memberhas taming-ring II, which surrounds th -t become standardized as acylindrical core hav- 9 at each end of the rotor. The outer end of ingaxially extending peripheral slots carrying each retaining-ring II isclosed by an end-plate concentric-coil field-windings. l2 which has acentrally disposed gas inlet open- The object of my present invention isto proing l3, and sometimes also additional openings vide such aturborotor with reamed-out radial M, for the admission of a gaseousventilatingoutlet-holes in the retaining-rings, and prefermedium, whichis usually hydrogen in modern ably also in the rotor teeth, so thatthese outletmachines, although air has sometimes been used. holes areshaped in the form of diflusers. By As pointed out in the FechheimerPatent No. this simple method, at a very trifling cost, I have1,927,890, filed December 19,1930, the ventilabeen able to achieve anincrease of at least three tion of these end-turns 9 has long been aproblem, or four percent in the rotor-output of turbo- Which FechheimerSolved y the e 0 i generators. This increase is due, I believe, to avelocities of the gaseous medium. thro h" reduction in the gas-pressurewhich is lost in n rr w sp c s between the end-turns 9, this producinghigh-velocity jets leaving these radial gaseous medium being thrownradially outwardly outlet-holes. The importance of recovering as y cntrif al for nd escapin through a much as possible of the energy inthese highplurality of substantially radial ventilatingvelocityjets-once said problem is given serious Openings or outlet-holes l5,which are provided considerationwill be appreciated when it is n a h d fr pla l Prior t my p sent inrealized that a large part of the totalavailable Vention. t ese O tlet-holes l5 have been of unigas-pressure,for ventilating a turbogenerator form cross-section, and they haveresulted in the rotor, is dissipated in producing these highformation01' high-Velocity je s of venti at ngvelocity jets, considering alsothat almost oneas. discharging from these holesc di to half of the totallosses in a turbogenerator is the my present ve t on, I ream out theseventilatfriction-loss, which is primarily the power reo es l5 in the ormof a diffuser, with an quired to ventilate the stator and rotor membersangle f about 11 (more or less) between the of the machine. And yet,notwithstanding the Opposite Side Walls Of the t at ng-holes l5, soalmost negligible cost of reaming these radial that theseVentilating-holes are of ng outlet-holes in the rotor, turborotors havebeen diameters as the gaseous v n ilating-medium standardized, for manyyears, with radial outpasses out through said ventilating-holes in thelet-holes of uniform cross-section. retaining-rings- My inventionconsists in the structures, comn h de i n of most tur o en rator rotors,it binations, parts, design-methods, and systems, is desirable, inaddition to the end-turn ventilah reinafter described and claimed, and mtion,-to ventilate the coil-sides 1 which lie in the trated in theaccompanying drawing, wherein; slots 5 Of the rotor-core l. A desirableway t0 ac- Figure 1 1 a, m wh t di m ti 51mph- I complish this coil-sideventilation is shown in the fled, longitudinal sectional view of a partof a Kllgore Patent No 2 094 358, filed May 29, 1 3

turbogenerator; according to which the rotor-slots 6 are provided Fig.21s a cut-away diagrammatic perspective wi h enlargements I 6, which rSh wn, in my view of one end of the rotor; and drawing, as beingunderneath the winding-receiv- Fllgs. 3 and 4 are detailed sectionsshowing the ing portion of the rotor-slots. Thus, the slotradialoutlet-holes through a retaining-ring and enlargements I6 constituteaxial ventilatingceiving the gaseous ventilating methrough arotor-tooth, respectively. 05 passages for re dium, for coiling thecoil-sides I of the rotorwinding. Near the axial center-line of themachine, as covered by the Kilgore patent, substantially radialoutlet-vents or holes I"! are provided, preferably in the form ofslightly inclined toothopenings or holes which are drilled through therotor-teeth l8, between the rotor-slots 6. These approximately radialtooth-holes l8 provide a communication between the rotor-periphery andthe axial ventilating-passages l6 of the rotor, so as to provideoutlet-ducts for the rotorventilation.

In accordance with my present invention, it is preferable also to reamout the outer portions of these outlet-holes in the rotor-teeth, asshown at 19, so that these tooth-openings will be of widening diametersas the ventilating-gas passes out therethrough to the rotor-periphery.Although the advantages which have been discovered to result from thereaming of these tooth-openings are not as great as the advantages whichhave been discovered to flow from the reaming of the outlet-holes in theretaining-rings, the cost of the reaming is so slight that it is usuallydesirable to ream both sets of outlet-holes, as described.

I claim as my invention:

1. A turbogenerator having a rotor comprising a slotted rotor-corehaving rotor-teeth between the rotor-slots, a concentric field-windinghaving coil-sides in the rotor-slots and having end-turns extendingbeyond each end of the rotor-core, a

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retaining-ring surrounding the end-turns at each end of the rotor, andan end-plate at the end 0! each retaining-ring, each end-plate having acentrally disposed gas-inlet opening for the admission of a gaseousventilating-medium, and each retaining-ring having a plurality ofapproximately radial diffuser-type ventilating-openings therethrough,being of widening diameters as the gaseous ventilating-medium passes outthrough said ventilating-openings in the retaining-rings.

2. The invention as defined in claim 1, characterized by saidrotor-slots having enlargements constituting axial ventilating-passages,and said rotor-teeth having approximately radial, diflusertypetooth-openings extending from the rotorperiphery into communication withsaid axial ventilating-passages, said tooth-openings being of wideningdiameters as the gaseous ventilatingmedium passes out therethrough tothe rotorperiphery.

MALCOLM D. ROSS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Criner Aug. 19, 1947

